Luminescent fuse plug



April 17, 1928.

L. F. MILLER LUIINESCENT FUSE PLUG Filed Oct. 22. 1926 Patented Apr. 11, 1928.

UNITED STATES LOUALLEN MILLER, 01 MINNEAPOLIS, MINNESOTA.

LUMINESOENT FUSE PLUG.

Application filed October 22, 1926. Serial No. 143,422.

with a material which, when subjected to light and especially when subjected to the intense light by the burning out of a fuse, will be rendered luminous for a considerable period of time, thereby indicating the plug that has been burned out or fused.

In the accompanying drawings, which illustrate the invention, like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. 1 is a front elevation of the fuse plug; and

Fig. 2 is an axial section taken on the line 22 of Fig. 1.

This plug comprises the usual elements, to wit: the hollow porcelain body 3 of metallic form, the threaded external metallic contact sleeve l, the axial contact 5, the fuse 6 connecting the contacts 4 and 5, the mica disc 7, and the clinched annular metallic disc container 8.

In accordance with my invention the mica disc 7 at its inner surface, is coated more or lesswith a luminescent salt such as zinc sulphide or calcium sulphide. I have with success used a luminescent salt known to the trade as scagrccn. The most eflicient means of applying the luminescent salt to the mica is to first spray the inner surface of the mica disc with collodion and then quickly and before the collodion sets to spray the same with the luminescent salt, as indicated at 9.

These fuse plugs are almost invariably contained in boxes or cabinets that are normally closed and hence kept dark so that the luminescentmaterial of the disc will remain dark. If, however, a fuse of the plug is blown out, the intense light produced will act upon the luminescent salt and render the same luminous for quite a long period of time, to wit, for half an hour or longer, and during such luminescent period it is of course very easy to identify the particular plug that has been blown out.

The cost of applying this luminescent sub stance to the plug is so slight that it may be treated as negligible and it is obvious accomplishes a very desirable result, to wit, the ready identification of a blown out plug.

What I claim is:

1. A fuse plug having applied theretoin the vicinity of its fuse a luminescent substance which, when the fuse is blown, will be rendered luminescent for an extended period of time.

2. A fuse plug having a mica disc and applied to the inner face a luminescent substance which, when a fuse is blown, will be rendered luminescent for an extended period of time.

3. A fuse plug having a mica disc and applied thereto a luminescent substance anchored thereto by collodion.

4;. An electric fuse device comprising an element which fuses with a flash of light un der an excess of current and means closely associated with the fusible element having the property of becoming distinctively luminous under the influence of the flashing of said fusible element and of maintaining for a substantially long period distinctive luminosity acquired through such flashings,,for the purpose specified.

5. A fuse plug of the character described having electric terminals, a hollow interior, and within the hollow interior an element which fuses with a flash of light under an excess of current, and having closely associated with the fusible element a surface coated with a substance having the property of becoming distinctively luminous under the influence of the flashing of the fusible element and of maintaining for a substantially long period distinctive luminosity acquired through such flashing, for the purpose specified.

In testimony whereof I aflix my signature.

LOUALLEN F. MILLER. 

